Vacuum IG units are known in the art. For example, see U.S. Pat. Nos. 5,664,395, 5,657,607, and 5,902,652, the disclosures of which are all hereby incorporated herein by reference.
FIGS. 1-2 illustrate a conventional vacuum IG unit (vacuum IG unit or VIG unit). Vacuum IG unit 1 includes two spaced apart glass substrates 2 and 3, which enclose an evacuated or low pressure space 6 therebetween. Glass sheets/substrates 2 and 3 are interconnected by peripheral or edge seal of fused solder glass 4 and an array of support pillars or spacers 5.
Pump-out tube 8 is hermetically sealed by solder glass 9 to an aperture or hole 10 which passes from an interior surface of glass sheet 2 to the bottom of recess 11 in the exterior face of sheet 2. It is noted, however, that a recess is not necessary in certain example embodiments and, instead, in certain example embodiments, the hole may pass from the interior surface of the glass to the exterior surface of the glass. A vacuum is attached to pump-out tube 8, e.g., via a pump cup, so that the interior cavity between substrates 2 and 3 can be evacuated to create a low pressure area or space 6. After evacuation, tube 8 is melted to seal the vacuum. Recess 11 retains sealed tube 8. Optionally, a chemical getter 12 may be included within recess 13.
Conventional vacuum IG units, with their fused solder glass peripheral seals 4, have been manufactured as follows. Glass frit in a solution (ultimately to form solder glass edge seal 4) is initially deposited around the periphery of substrate 2. The other substrate 3 is brought down over top of substrate 2 so as to sandwich spacers 5 and the glass frit/solution therebetween. The entire assembly including sheets 2, 3, the spacers, and the seal material is then heated to a temperature of approximately 500° C., at which point the glass frit melts, wets the surfaces of the glass sheets 2, 3, and ultimately forms hermetic peripheral or edge seal 4. After formation of edge seal 4, a vacuum is drawn via the tube to form low pressure space 6.
The pressure in space 6 may be reduced by way of an evacuation process to a level below about 10−2 Torr, more preferably below about 10−3 Torr, and most preferably below about 5×10−4 Torr. To maintain such low pressures below atmospheric pressure, substrates 2 and 3 are often hermetically sealed to one another by edge seal 4. The small, high strength support spacers 5 are provided between substrates 2, 3 in order to maintain separation of the approximately parallel substrates against atmospheric pressure. It is often desirable for spacers 5 to be sufficiently small so that they are visibly unobtrusive. Once the space between the substrates 2, 3 has been evacuated, the tube may be sealed, e.g., by melting.
The tube 8 oftentimes is located in the corner of one of the substrates, e.g., as shown in FIGS. 1-2. The tube 8 may be made of glass and protrude above the surface of the substrate in which it is located, e.g., to facilitate melting thereof in a sealing process. The process of melting a glass tube to a degree sufficient for the melted glass to seal the tube closed, while maintaining the vacuum within the VIG, is commonly referred to as tip-off. Lasers are sometimes used to seal the glass. One current solution involves the laser being positioned within a heated oven above the pump cup used in the evacuation. In some cases, the oven may be a multiple level oven in which multiple VIG subassemblies are processed in parallel. Provisions are made so that there is laser access to the various units in the multi-level oven. The temperature within the oven may reach as high as and sometimes even higher than 300 degrees C.
Most commonly used laser sources are orientated perpendicular to their targets. This is the case with current laser tip-off systems. Because VIG unit subassemblies typically are conveyed in a manner that is “face up” or substantially parallel to the ground, current laser tip-off systems orient their laser sources above the tube. A laser source in such a system emits its laser beam downward, through a quartz window, and onto the tube to melt it.
FIG. 3 is an example of a current multi-level laser tip-off system. As can be seen from FIG. 3, the VIG subassembly 1′ rolls on rollers 17 or is conveyed on supports into and/or through the oven 21. Openings 23 are formed in the sidewall 25 and accommodate an insulated box 27 that houses the laser source 29. The insulated box 27 also typically is cooled to keep temperatures therein at a level sufficiently low so as to avoid damaging the laser source 29. The laser source 29 emits a laser beam 31 through a quartz window 33 formed in the insulated box 27. The laser beam 31 contacts and seals the pump-out tube.
Unfortunately, there are several drawbacks associated with the current approach shown in and described in connection with FIG. 3. The laser is enclosed in an insulated and cooled box to reduce the likelihood of damage to the laser source. This arrangement complicates the design and oftentimes plural individualized cooling subsystems. This arrangement also typically include access doors and/or panels that open to allow the laser to be inserted into the oven, removed when damaged, etc. Providing access to the laser, however, has been found to result in temperature uniformity issues within the body of the oven and on the surface VIG subassembly. To compensate for these non-uniformities, additional controls and heating capabilities are provided to reduce the non-uniformities. Another disadvantage relates to the space between subsequent levels, which is fairly large since each stage includes rollers, accommodates a VIG unit, and has an insulated and cooled box housing a laser. This increases vertical space requirements and/or restricts how many units can be stacked on top of one another.
Thus, it will be appreciated that there is a need in the art for improved techniques for sealing the pump-out tubes used in VIG units.
One aspect of certain example embodiments relates to enabling the laser source to be located outside of the oven by directing the laser beam through a sidewall of the oven to a laser mirror mounted above the pump cup and/or tube, with the mirror, in turn, reflecting the laser beam downward onto the tube (and possibly through a quartz or other window of the pump cup).
In certain example embodiments of this invention, a laser tip-off system for a vacuum insulating glass (VIG) unit is provided. An oven has an oven interior and a sidewall in which at least one opening is formed, with at least one window being located in the at least one opening. At least one reflector is located in the oven interior. At least one laser source is located outside of the oven, with the at least one laser source being aligned with the window and configured to emit a laser beam towards the at least one reflector. The at least one reflector is oriented within the oven interior to cause laser beams emitted from the at least one laser source to be redirected towards a pump-out tube of a VIG unit subassembly provided to the oven interior.
In certain example embodiments of this invention, a kit is provided. The kit comprises at least one vacuum insulating glass (VIG) unit subassembly including a glass pump-out tube to be sealed and a pump cup located over the pump-out tube; and a laser tip-off system for sealing the pump-out tube of the VIG unit subassembly. The system includes an oven having an oven interior and a wall in which at least one opening is formed, with at least one window being located in the at least one opening. At least one reflector is located in the oven interior. At least one laser source is located outside of the oven, with the at least one laser source being aligned with the window and configured to emit a laser beam towards the at least one reflector. The at least one reflector is oriented within the oven interior to cause laser beams emitted from the at least one laser source to be redirected towards the pump-out tube of the VIG unit subassembly when the VIG unit subassembly is provided to the oven interior.
In certain example embodiments of this invention, a method of making a vacuum insulating glass (VIG) unit is provided. There is provided an oven having an oven interior and a sidewall in which an opening is formed. A reflector is located in the oven interior and at least one window is located in the sidewall. A VIG unit subassembly is supplied to the oven, with the VIG unit subassembly having a pump-out tube to be sealed. A laser beam is emitted from a laser source located outside of the oven, with the laser beam being emitted through the at least one window and towards the reflector and being redirected by the reflector towards the pump-out tube to be sealed. The pump-out tube is melted using the laser beam in making the VIG unit.
In certain example embodiments of this invention, a method of making vacuum insulating glass (VIG) units is provided. There is provided an oven having an oven interior and a wall in which a plurality of openings are formed, with each opening corresponding to a different level of the oven and each level being suitable to accommodate a respective VIG unit subassembly. A laser-grade mirror is located in the oven interior at each said level, and at least one window is located in each said opening. VIG unit subassemblies are supplied to the oven at different respective levels thereof, with the VIG unit subassemblies each having a pump-out tube to be sealed. Laser beams are emitted from laser sources located outside of the oven, with each said laser beam being (a) emitted through an associated opening and any windows of the associated opening, (b) directed towards the mirror associated with that opening, and (c) redirected by the mirror towards the pump-out tube of the VIG unit subassembly at the corresponding level. The pump-out tubes are melted in making the VIG units.
In certain example embodiments, a laser tip-off system for a vacuum insulating glass (VIG) unit is provided. An oven has an oven interior and a sidewall in which at least one opening is formed, with at least one window being located in the at least one opening. At least one reflector is located in the oven interior. At least one laser source is located outside of the oven, with the at least one laser source being aligned with the window and configured to emit a laser beam towards the at least one reflector. The at least one reflector is oriented within the oven interior to cause laser beams emitted from the at least one laser source to be redirected towards a pump-out tube of a VIG unit subassembly provided to the oven interior. A vision system is configured to provide positional data for facilitating the melting of the pump-out tube. A lighting system is located remote from the oven. A quartz rod is configured to convey light from the lighting system to an area proximate the pump-out tube and through VIG unit so as to increase contrast in that area.
In certain example embodiments, a kit is provided. The kit includes at least one vacuum insulating glass (VIG) unit subassembly, with the VIG unit subassembly including a glass pump-out tube to be sealed and a pump cup located over the pump-out tube; and a laser tip-off system for sealing the pump-out tube of the VIG unit subassembly. The system comprises an oven having an oven interior and a wall in which at least one opening is formed, with at least one window being located in the at least one opening; at least one reflector located in the oven interior; at least one laser source located outside of the oven, with the at least one laser source being aligned with the window and configured to emit a laser beam towards the at least one reflector; an artificial vision system configured to (a) detect the placement of the VIG unit subassembly within the oven and (b) provide a signal to at least one processor of a control unit, with the signal being interpreted by the at least one processor to determine whether a vertical adjustment of the at least one laser source is to be made to adjust the area on which the laser beam is to be focused in dependence on the detected placement; and a quartz rod configured to convey light from a lighting system to an area proximate the pump-out tube and through VIG unit so as to increase contrast in that area. The at least one reflector is oriented within the oven interior to cause laser beams emitted from the at least one laser source to be redirected towards the pump-out tube of the VIG unit subassembly when the VIG unit subassembly is provided to the oven interior.
In certain example embodiments, a method of making a vacuum insulating glass (VIG) unit is provided. An oven having an oven interior and a sidewall in which an opening is formed is provided. A reflector is located in the oven interior and at least one window is located in the sidewall. A VIG unit subassembly is supplied to the oven, with the VIG unit subassembly having a pump-out tube to be sealed. The pump-out tube is located using a vision system and a contrast-enhancing backlight, with the contrast-enhancing backlight being originated from a light source located external to the oven and being conveyed to the oven interior via a quartz rod. A laser beam is emitted from a laser source located outside of the oven, with the laser beam being emitted through the at least one window and towards the reflector and being redirected by the reflector towards the pump-out tube to be sealed. The pump-out tube is melted using the laser beam in making the VIG unit.
In certain example embodiments, a method of making vacuum insulating glass (VIG) units is provided. An oven having an oven interior and a wall in which a plurality of openings are formed is provided, with each opening corresponding to a different level of the oven and each level being suitable to accommodate a respective VIG unit subassembly. A laser-grade mirror is located in the oven interior at each said level, and at least one window is located in each said opening. VIG unit subassemblies are supplied to the oven at different respective levels thereof, with the VIG unit subassemblies each having a pump-out tube to be sealed. At each level, the pump-out tube of the corresponding VIG unit subassembly is located, using a vision system and a contrast-enhancing backlight provided at that level, with the contrast-enhancing backlight being originated from a light source located external to the oven and being conveyed to the oven interior via a quartz rod. Laser beams from laser sources located outside of the oven are emitted, with each said laser beam being (a) emitted through an associated opening and any windows of the associated opening, (b) directed towards the mirror associated with that opening, and (c) redirected by the mirror towards the pump-out tube of the VIG unit subassembly at the corresponding level. The pump-out tubes are melted in making the VIG units.
In certain example embodiments, a laser tip-off system for a vacuum insulating glass (VIG) unit is provided. The system includes an oven; at least one laser source for melting a pump-out tube of the VIG unit; a vision system configured to provide positional data for facilitating the melting of the pump-out tube; a backlighting system located remote from the oven; and a quartz rod configured to convey light from the lighting system to an area proximate the pump-out tube and through VIG unit so as to increase contrast in that area and facilitate location of the pump-out tube by the vision system.
The features, aspects, advantages, and example embodiments described herein may be combined to realize yet further embodiments.